Audio system for a computer

ABSTRACT

A computer audio system includes an audio codec and a tone controller. The audio codec is operably coupled to receive audio information, which includes tone control settings, PCM digital audio inputs and PCM digital audio outputs. In addition, the audio codec may receive audio information as analog input signals via a line-in, a CD input, or an auxiliary input. Based on the audio information, the audio codec provides a first stereo output, a second stereo output and a monotone audio output. The tone controller is operably coupled to the audio codec and includes a low pass filter, a high pass filter, a band pass filter, and a summing module. The low pass filter is operably coupled to filter the monotone audio output and isolates bass components of the audio signal being processed. By further coupling a volume control module to the low pass filter, the bass component of the audio signal being processed may be varied. The high pass filter is operably coupled to filter the first stereo audio signal to pass treble components of the audio signal being processed. Similarly, a volume control module may be coupled to the high pass filter to provide tone control for the treble components of the audio signal being processed. The band pass filter is operably coupled to filter the second stereo audio output, which passes midband components of the audio signal being processed. Similarly, a volume control module may be coupled to the band pass filter such that midband components of the audio signal being processed may be adjusted. The summing module sums the bass component, treble component and midband component of the audio signal being processed to produce a tone controlled audio output.

This patent application is claiming priority under 35 USC § 120 as acontinuing patent application to patent application having a title of AComputer Audio System, a Ser. No. of 09/690,215, and a filing date ofOct. 17, 2000 now U.S. Pat. No. 6,931,139.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to computers and more particularly toaudio processing in computers.

BACKGROUND OF THE INVENTION

As is known, personal computers (PC) and laptop computers include audioprocessing circuitry. Such audio processing circuitry allows a computerto play CDs, DVDs, etc. and produce audible sound therefrom. Current PCsand laptop computers include three audio jacks to facilitate theprocessing of audio. The three jacks are typically labeled line-in,microphone, and line-out. The line-in audio jack receives analog audiosignals from external devices such as a CD player, cassette player, etc.The audio processing circuitry receives the analog audio signalsconverts the analog signals into digital signals, which can bemanipulated by the computer. The audio processing circuitry alsoreceives digital audio signals from the computer, converts them toanalog signals, and provides the analog signals to speakers via theline-out jack. The digital audio signals may also be received viaplayback of a CD, an internal CD driver, etc. The audio processingcircuitry may also receive analog audio signals via the microphone audiojack and convert these analog signals into digital audio signals forprocessing by the computer.

Typically, a computer will include an audio codec to facilitate theprocessing of audio signals. As is known, an audio codec receives analogsignals and converts them to digital signals and receives digitalsignals and converts them to analog signals. While the audio codecprovides a wide variety of audio processing functions, it does notprovide tone control. As is known, tone control allows for the adjustingof amplitudes of analog signals within certain frequency ranges. As isalso known, the audio frequency range is generally between 20 Hz to 20KHz, which may be divided into multiple components. For example, basscomponent signals are generally signals having frequencies less than 200Hz and treble component signals are generally signals having frequenciesgreater than 4 Khz.

To enhance a user enjoyment of computer audio and to compensate forimperfections in low-end speakers' ability to accurately reproducemusic, it is desirable to provide tone control. Therefore, a need existsfor a computer audio system that provides tone control options.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic block diagram of a computer audio systemin accordance with the present invention;

FIG. 2 illustrates a more detailed schematic block diagram of the audiocodec and tone controller of the computer audio system of FIG. 1;

FIG. 3 illustrates a schematic block diagram of an audio codec includingtone control functionality in accordance with the present invention;

FIG. 4 illustrates an alternate detailed schematic block diagram of theaudio codec and tone controller of FIG. 1;

FIG. 5 illustrates an alternate schematic block diagram of an audiocodec including tone control functionality in accordance with thepresent invention; and

FIG. 6 illustrates a schematic block diagram of the tone controllerfunctionality in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Generally, the present invention provides a computer audio system thatincludes an audio codec and a tone controller. The audio codec isoperably coupled to receive audio information, which includes tonecontrol settings, PCM digital audio inputs and PCM digital audiooutputs. In addition, the audio codec may receive audio information asanalog input signals via a line-in, a CD input, or an auxiliary input.Based on the audio information, the audio codec provides a first stereooutput, a second stereo output and a monotone audio output. The tonecontroller is operably coupled to the audio codec and includes a lowpass filter, a high pass filter, a band pass filter, and a summingmodule. The low pass filter is operably coupled to filter the monotoneaudio output and isolates bass components of the audio signal beingprocessed. By further coupling a volume control module to the low passfilter, the bass component of the audio signal being processed may bevaried. The high pass filter is operably coupled to filter the firststereo audio signal to pass treble components of the audio signal beingprocessed. Similarly, a volume control module may be coupled to the highpass filter to provide tone control for the treble components of theaudio signal being processed. The band pass filter is operably coupledto filter the second stereo audio output, which passes midbandcomponents of the audio signal being processed. Similarly, a volumecontrol module may be coupled to the band pass filter such that midbandcomponents of the audio signal being processed may be adjusted. Thesumming module sums the bass component, treble component and midbandcomponent of the audio signal being processed to produce a tonecontrolled audio output. With such a computer audio system, tone controlmay be readily provided in PCs and laptop computers without the need forexpensive equalizing circuitry or other expensive tone control circuits.

The present invention can be more fully described with reference toFIGS. 1 through 6. FIG. 1 illustrates a schematic block diagram of thecomputer audio system 10 that includes a central processing unit (CPU)12, system memory 14, a chip set 16, an audio codec 18, a tonecontroller 20, and a pair of speakers 22 and 24. The functionality of acentral processing unit 12, the system memory 14, and the chip set 16 iswell known thus no further discussion will be presented except toillustrate the present invention. As shown, the chip set 16 communicateswith the audio codec 18 via an AC link 26. The information conveyed overthe AC link 26 is in accordance with the AC 97 specification Rev. 1.03and subsequent revisions thereto. In general, the information conveyedover the AC link 26 includes PCM digital audio inputs 46, PCM digitalaudio outputs 48 and audio information 50. The audio information 50includes volume settings, multiplexor selection settings, tone controlsettings (i.e. bass settings, midrange settings, and treble settings)and other control information in accordance with the AC 97specification.

The audio codec 18 receives computer audio inputs 27 via one or more ofa line input 30, a CD input 32 and an auxiliary input 34. As is known,these inputs provide analog audio signals to the audio codec 18. Theaudio codec 18, which may be a STAC9721 manufactured and distributed bySigmaTel, Inc., manipulates the analog signals, analog audio signalsand/or digital audio signals to produce two stereo outputs and amonotone output 44. The first stereo output may be the line-out, whichincludes a line-out right channel 36 and a line-out left channel 38. Thesecond stereo output may be a line-level output that includes aline-level out right channel 40 and a line-level out left channel 42.The tone controller 20 is operably coupled to receive the line-out rightand left channels 36 and 38, the line-level out left and right channels40 and 42 and the monotone channel 44. Based on these inputs, the tonecontroller 20 produces a tone controlled stereo output that is providedto the computer audio outputs 28. The computer audio output may be theline-out audio jack of a PC or laptop computer. Alternatively, thecomputer audio output 28 may be provided directly to speakers 22 and 24that are included in the PC or laptop.

FIG. 2 illustrates a more detailed schematic block diagram of the audiocodec 18 and tone controller 20. As shown, the audio codec 18 includes aright mixer 60, a left mixer 61, a digital to analog converter 62, aplurality of volume controller 64, 66, 68, 70 and 72, a summing module74, and a register 76. The register 76 is operably coupled to receivethe audio information 50 via the AC link 26. Such audio information 50may include volume settings for each of the volume controllers 64through 72, bass tone settings, treble tone settings, mid component tonesettings, etc.

The digital to analog converter 62 is operably coupled to receive thePCM digital audio input 46 and convert the digital audio signal into ananalog audio signal. The right and left mixers 60 and 61 are operablycoupled to mix one or more of the line input 30, CD input 32, auxiliaryinput 34 or the output of DAC 62. The output of the right mixer 60 isprovided to volume controller 64, volume controller 66, and the summingmodule 74. The volume controller 64 provides volume control for theline-out right channel 36, while volume control of 66 provides volumecontrol for the line-level output right channel 40. The output of mixer61 is provided to the summing module 74, the volume controller 70 andthe volume controller 72. The volume controller 70 controls the volumefor the line-level output of the left channel 42 and volume controller72 provides the volume control for the line-out left channel 38. Thesumming module 74 sums the output of the right channel mixer 60 with theoutput of the left channel mixer 61 to produce a monotone signal. Volumecontroller 68 controls the volume for the monotone output 44.

The tone controller 20 includes a high pass filter 78 (which may have acorner frequency of 1-4 KHz), a band pass filter 80 (which may havecorner frequencies of 100 Hz and 1-4 KHz), a low pass filter 82 (whichmay have a corner frequency of 100 Hz), a band pass filter 84 (which mayhave corner frequencies of 100 Hz and 1-4 KHz), a high pass filter 86(which may have a corner frequency of 1-4 KHz), a right summing module97 and a left summing module 98. The low pass filter 82 is operablycoupled to receive the output of the volume controller 68 and thusfilters the monotone signal 44. As such, only the bass component of themonotone signal is provided. As is generally known, bass signals aretypically monotone in audio recordings. High pass filter 78 is operablycoupled to filter the line-out right channel 36 such that only thetreble components associated with the line-out right channel 36 arepassed. Band pass filter 80 is operably coupled to receive theline-level output right channel 40 and pass the mid-components of theline-level right channel out 40. The right summing module 97 receivesthe output of high pass filters 78, band pass filter 80, and low passfilter 82 to produce a right tone controlled audio output 88. As shown,the right tone controlled audio output 88 includes a bass component 96,a mid-band component 94, and a treble component 92.

The band pass filter 84 is operably coupled to receive the line-levelout left channel 42 and pass only the mid-band components associatedtherewith. The high pass filter 86 is operably coupled to receive theline-out left channel 38 and pass the treble components thereof. Theleft summing module 98 is operably coupled to receive the output of lowpass filter 82, band pass filter 84 and high pass filter 86 to produce aleft tone controlled audio output 90. The left tone controlled audiooutput 90 also includes a treble component, a mid-band component and abass component. As such, by adjusting the volume settings for volumecontrollers 64 through 72, tone control may be readily provided in acomputer environment with minimal additional circuitry and minimaladditional expense. As one of average skill in the art will appreciate,the band pass filters 80 and 84 may be deleted such that all frequencycomponents are presented to the summing nodes 97 and 98.

FIG. 3 illustrates an audio codec that includes at least portions of thetone control functionality as separate components or as part of theaudio processing circuitry. The audio codec includes the right and leftmixers 60 and 61, the digital to analog converter 62, the volumecontroller 64 through 72, the semi-module 74, register 76 and tonecontrol circuitry. The tone control circuitry includes the high passfilter 78, the band pass filter 80, the low pass filter 82, the bandpass filter 84, the high pass filter 86, the right summing module 97 andthe left summing module 98. The functionality of the audio codec 18including the tone control circuitry functions in a similar manner tothe circuit of FIG. 2. The primary difference between the circuit ofFIG. 3 and the circuit of FIG. 2, is that the audio codec 18 of FIG. 3includes the tone control circuitry. An advantage of the audio codec ofFIG. 3 is that sound card manufactures and motherboard manufacturerswould not need to include the additional circuitry associated with thetone controller 20.

FIG. 4 illustrates a schematic block diagram of an alternate coupling ofthe audio codec 18 with tone controller 20. In this embodiment, theaudio codec 18 does not include a monotone output. As such, the audiocodec produces a line-out right audio signal 36, a line-level out rightaudio signal 40, a line-level out left audio signal 42 and a line-outleft audio signal 38. The adjusting of the volume controller 64, 66, 70and 72 will be controlled via data stored in register 76 as previouslydiscussed.

The tone controller 20 includes a notch filter 100, band pass filter 80,band pass filter 84, notch filter 102, right summing module 97 and leftsumming module 98. The band pass filter 80 passes mid-band components ofthe line-level out right channel 40 to the right summing module 97. Thenotch filter 100 passes bass components and treble components of theline-out right channel 36 to the right summing module 97. The rightsumming module sums the output of the notch filter 100 and the band passfilter 80 to produce the right tone controlled audio output 88. In thisembodiment, the volume setting for volume controller 64 controls thenotched output 104 as such, the bass and treble components of the righttoned controlled audio output will be set using the same volume inputs.

The band pass filter 84 passes the mid-band components of the line-levelout left channel 42 to the left summing module 98. The notch filter 102passes the bass components and treble components of the line-out leftchannel 38 to the left summing module 98. The left summing module 98sums the outputs of band pass filter 84 and notch filter 102 to producethe left tone controlled audio output 90.

FIG. 5 illustrates the audio codec 18 including the right mixer 60, leftmixer 61, DAC 62, volume controllers 64, 66, 70 and 72, register 76 andtone control circuitry. The tone control circuitry includes notch filter100, band pass filter 80, band pass filter 84, notch filter 102, rightsumming module 97 and left summing module 98. The functionality of theaudio codec 18 of FIG. 5 that includes the tone control functionality,operates in a similar manner as the circuit described with reference toFIG. 4.

FIG. 6 illustrates a schematic block diagram of the tone controllerfunctionality 20. As shown, band pass filter 80 includes capacitors 118and 122 and a resistor 120. As coupled, the band pass filter 80 passesmid-band components of the line-level out right channel 40 via resistor128 to the negative input of operational amplifier 110. The negativeinput of operation amplifier 110 functions as the right summing module97. The operational amplifier 110 includes feedback components 130 and132.

The high pass filter 78 includes capacitor 124 and resistor 126. Ascoupled, the components of the high pass filter 78 pass the treblecomponents of the line-out right channel 36 to the negative input ofoperational amplifier 110. The low pass filter 82 includes resistor 114and capacitor 116. As coupled, the components of low pass filter 82 passthe low frequency components of the monotone signal 44 to the negativeinput of operational amplifier 110 via resistor 134. As one of averageskill in the art will appreciate, the capacitor and resistor values ofthe filters 80, 78 and 82 will be sized to pass the appropriatefrequency ranges of bass signal components, mid-band signal componentsand treble components of audio signals.

The band pass filter 84 includes capacitors 136, 140 and resistor 138.As coupled, the components of band pass filter 84 pass the mid-bandcomponents of the line-level out left channel 42 to the negative inputof operational amplifier 112 via resistor 142. High pass filter 86includes capacitor 146 and resistor 148. The components of the high passfilter 86 pass the treble components of the line-out left channel 38 tothe negative input of operational amplifier 112. The negative input ofoperational amplifier 112 is also operably coupled via resistor 144 tothe output of low pass filter 82. The operational amplifier 112 includesfeedback components 150 and 152 to produce the left tone controlledaudio output 90.

The preceding discussion has presented a computer audio system thatprovides tone control with minimal additional circuitry and minimaladditional costs. As such, as computer features enhance, the presentinvention provides enhanced audio enjoyment for users of computers withminimal additional cost to computer manufacturers. As one of averageskill in the art will appreciate, other embodiments may be derived fromthe teachings contained herein without deviating from the scopes of theclaims. For example, additional filters may be included, where thefilters pass different frequency components of the audio signal. As afurther example, the filters may have a customized frequency response(e.g., nulls and/or peaks) to compensate for the environment in whichthe speakers reside and/or the quality of the speakers. Still further,the summing modules 97 and 98 may be implemented on chip with the audiocodec while the filters would be off-chip components.

1. A computer audio system comprises: an audio codec operably coupled toreceive audio information and to provide a first stereo audio output, asecond stereo audio output, and a monotone audio output based on theaudio information; and a tone controller operably coupled to the audiocodec, wherein the tone controller includes: a low pass filter operablycoupled to filter the monotone audio output, wherein the low pass filterpasses a bass component of the monotone audio output substantiallyunattenuated and attenuates higher frequency components of the monotoneaudio output; a high pass filter operably coupled to filter the firststereo audio output, wherein the high passes filter passes a treblecomponent of the first stereo audio output substantially unattenuatedand attenuates lower frequency components of the first stereo audiosignal; a band pass filter operably coupled to filter the second stereoaudio output, wherein the band pass filter passes a mid band componentof the second audio output substantially unattenuated and attenuates lowfrequency components and high frequency components of the second stereoaudio signal; and a summing module operably coupled to sum the basscomponent, the treble component, and the mid band component to produce atone controlled audio output.
 2. The computer audio system of claim 1,wherein at least one of the low pass filter, the high pass filter, andthe band pass filter further comprise a frequency response customizedbased on parameters of a computer including the computer audio system.3. The computer audio system of claim 1, wherein the summing modulefurther comprises an operational amplifier having a first input, asecond input, and an output, wherein the first input is operably coupledto a reference voltage and the second input is operably coupled to sumthe bass component, the treble component, and the mid band component. 4.A computer audio system comprises: an audio codec operably coupled toreceive audio information and to provide a first stereo audio output anda second stereo audio output based on the audio information; a tonecontroller operably coupled to the audio codec, wherein the tonecontroller includes: a notch filter operably coupled to filter the firststereo audio output, wherein the notch filter passes a bass componentand a treble component of the first stereo audio output and attenuates amid-band component of the first stereo audio output to produce a notchedaudio output; a band pass filter operably coupled to filter the secondstereo audio output, wherein the band pass filter passes a mid-bandcomponent of the second stereo audio output and attenuates a basscomponent and a treble component of the second stereo audio output toproduce a band pass audio output; and a summing module operably coupledto sum the notched audio output and the band pass audio output toproduce a tone controlled audio output.
 5. The computer audio system ofclaim 4, wherein at least one of the notch filter and the band passfilter further comprise a frequency response customized based onparameters of a computer including the computer audio system.
 6. Thecomputer audio system of claim 4, wherein the summing module furthercomprises an operational amplifier having a first input, a second input,and an output, wherein the first input is operably coupled to areference voltage and the second input is operably coupled to sum thebass component, the treble component, and the mid band component.